The USA & canadain Pontiacs never had any plans of putting any big block chevy engine in any Pontiac A-body. Lets get that out of the way first. The SD 455 was rated at 310 HP & in 74 it was dropped down to 305 HP. So to start the BBC was never in any way worried about having any HP wars with the chevy engine. The cvevy engine was rated at 8.3:1 compression in the chevell ss & the SD 455 is rated at 8.75:1 which again makes the Pontiac engine higher in compression. Also if you look back at the 73 cars the only division that didn't get a 4 spd with the 455 was Pontiac . All the other divisions got a 4 spd. with there biggest engine choise. The reason was the Pontiac enginge had to much torque to put the 4 spd's behind it because there would have been to many werr. issues if they were to put the 4 spd behind the 455 or the SD 455, so Pontiac was the only one not to get a 4 spped behind there 455's.Next the test car back in Aug. of 73 in the Cars magizine had the 73 GTO SD 455 car running in the 1'4 mile at 13 flat at 99 MPH on the polyglass GT tires. The biggest reason the SD 455 didn't get into the A-body in 73 was because of late emmisions testing too. Pontiac got caught with the test figures being fudged a bit & they didn't have time to retest it in the A-body so they just decided to drop it for the A-body & put it in the F-body because they already had the correct figures for it. Next for the RA system on the A-body, it had nothing to do with the noise limits of the RA system it was problems with the shaker being open & getting water down in the shaker & causeing carb problems. It was a mandotory item if you got the SD 455 but with the advent of no SD engine & the problems with the shaker on it they just dropped it on all but a few cars that had already gotten out & the handful of parts that made it out into the parts system. Now for the next item & 1 that is always an item for debate. The NASA hood. Pontiac has always called it a NASA hood. Ther is no debate that the type of scoop that is in the hood is a naca duct. BUT , Pontiac called it in ALL of the printed items , weather it be sales or parts or any type of printed material it has & always will be called the NASA hood. The reason they call it the NASA hood is Pontiac was using it to tie into the space race at that time to get so well needed extra sales promotion. Pontiac was laggging behind in sales & when they started to use the term tied into the space race calling it the NASA hood things picked up a bit. But not a lot . But no where will you ever see it called a naca hood in any Potiac print EVER. It may be a naca duct BUT, PONTIAC calls it a NASA HOOD & that is where it should end. If anyone can show any printed items from Pontiac that calls it a naca hood get it out & show the world your proof, if not give in & call it as Pontiac has always. The NASA hood.